Gaseous electric discharge device



March 16, 1937- H. A. STONE ET AL 2,

} GASEOUS ELECTRIC DISCHARGE DEVICE Filed Feb. 9, 1934 ope,

ATTORNEYS Patented Mar. 16,. 1937- GASEOUS ELECTRIC nrscnanec onvrcnHarry A. Stone and Frank Schaeler, Detroit, Mich.

Application February 9, 1934, Serial No.'710,4l9

20 Claims. (Cl. 176122) This invention relates to improvements in to therelease of gases normally occluded by the gaseous electric dischargedevices and more parmetallic electrodes and to the fact that thepositicularly to a means for protecting and preservtiveions are notpositively prohibited from find-= ing the cathodes thereof. ing theexterior surface of the cathode. Fur- In the process of making gaseousdischarge ther, if the voltage between the cathode and lamps it isimportant to expel all gases normally anode becomes abnormally high, thebombardoccluded in the metallic electrodes and likewise ment of thecathode by the positive ions causes to expel all gases which cling tothe tube itself. abnormal heating of the cathode, which, in turn This isdone by heating the electrodes to a cherry increases the saturationcurrent. The undue red under an electron bombarding process whileheating from these or any other causes wears 10 repeatedly subjectingthe tube to the suction of away the cathode and has a very deleteriouseffect a vacuum pump. The temperatures to which the on the life of thetube. It is, therefore, another cathodes are thus subjected are greaterthan object of the invention to provide a means for 18 those employedduring normal operation in order residence immediately adjacent thecathode for that undue further expulsion of gases by the elecabsorbingthe gases expelled by the cathode durtrodes will not later occur. Due tothe abnormal ing normal operation to prevent undue heating heating andalso due to the fact that the tubes and sputtering with the resultantdisintegration are always subjected to this process while lying of theelectrode and which will thus force the on a work-bench or table, it isnecessary to suppositive ions to find the interior of the cathode 2 portthe electrodes in spaced relation from the for electron liberation. Thissupport thus acts tube as otherwise the electrode may contact the as amechanical shield against the positive ions glass, a sin partial fusionand lat r breakage. to the extent that it largely removes the cause ofIt is therefore an object of this invention to proexternal cathodebombardment, permitting the vide an improved support for the electrodewhich a positive ions to find the interior thereof and. it

will effectively support and heat insulate the also acts as a chemicalscavenger for extraneous 25 electrode from the glass tube. gases.

It is well understood that it is impossible to Disintegration of thecathode as indicated compl ly e p all gases from a metallic elecabovebecomes noticeable to an observer because trade even by bombardmentunder abnormal of the metallic deposit on the interior of the glasstemperatures. Also, while the rare gases may tube. This deposit of puremetal has the capacm be obtained in highly purified condition, they ityto absorb or occlude the rare gas and has been contact glass surfacesand lubricated stop cocks known to absorb such sizable amounts of thegas during introduction and thereby become more or as to prevent furtheroperation of the tube. It 5 less contaminated. The presence of suchforeign is therefore a further object to provide a cathode gases altersthe desired color, requires greater support having the inherentproperties of clean- 3% current and may become suflicient in quantity toing up foreign gases as described above and to preclude operation. It istherefore another object extend this support forwardly of the cathode byof this invention to provide means in the tube an appreciable amount topreclude a deposition 4 which, as here illustrated, is inherent in theype of the metal on the interior of the tube for a m of electrodesupport aforementioned, to clean up long period of time. or scavenge allresidual foreign gases in the elec- In such devices where mercury vaporis emtrode and tube. played with a rare gas to produce a blue light itDuring the operation of a gaseous discharge is sometimes difficult toobtain prompt vaporiza- 5 tube the cathode is given a sufficientpotential to tion of the' mercury. It is therefore another obdischargeelectrons which break down or lonize ject of this invention to provide acathode supmolecules of the gases by collision. The electrons port asdescribed above, containing a material, thus freed travel with theoriginal or primary such as sodium or potassium, which will combineelectrons toward the anode while a greater quanwith the mercury to forman amalgam thereby tum of the positive ions seek the cathode tolibretaining'a supply of mercury adjacent the hot- 5@ I erate additionalelectrons. The positive ions can, test region in the tube for promptvaporization i under certain conditions, combine with electrons uponre-activation.

at the surface of the cathode and thus form a In carrying our inventioninto efiect we emlayer of gas thereon extending to the exterior ploy asilicate compound of the alkali or alkasurface of the cathode. This isdue very largely line earth groups, preferably in a finely divided 5acondition, as for instance, glass wool, as a. sup port for theelectrode, the wool being adapted to fuse by an amount sufiicient torender a quantity of free alkali, as sodium or potassium or 5 barium orstrontium, available for use as a scavanger or "getter of foreign gasesand as a means for forming an amalgam where mercury is used.

Other objects and advantages either directly described or implied willbecome hereinafter more fully apparent as reference is had to theaccompanying drawing, wherein our invention is illustrated by way ofexample and in which- Figure 1 is an elevation of a U-shaped gaseouselectric discharge tube, partially broken away to clearly illustrate ourinvention;

Fig. 2 is an enlarged vertical sectional view of one end of the tubeillustrated in Figure 1 with an electrode and our improved supporttherein, and

2 Fig. 3 is a transverse section taken along the line 3-3 of Figure 2.

More particularly, I indicates a hollow glass tube having an electrode 2sealed in each end thereof. The tube is adapted to be filled with a raregas, such as neon, argon and the like either with or without an amountof mercury. Each electrode is composed of an energizing lead wire 3 anda tubular bell-shaped electrode proper 4, usually made of copper. Eachelectrode is surrounded or wrapped with a finely divided silicatecompound 5, preferably glass wool. The wool covers a substantial area ofthe outer surface of the electrode 4 and extends slightly out-- p wardlythereof as indicated at 6.

Upon heating the electrode by current from the lead wire 3 there is aslight fusion of the glass wool with the electrode, releasing anappreciable amount of alkali or alkaline earth metal so that a quantityof free sodium, potassium, barium or strontium, etc., is available atthe electrode for absorption of any occluded gas released by theelectrode and also for scavenging any foreign gas within the tube. Thewool, by encircling the open end of the electrode also acts as amechanical screen for forcing the positive ions to the interior of thecathode for further electron liberation.

The slight fusion of the wool does not interfere with the electrodesupporting function of the wool. In fact, from this standpoint, there isonly a, sumcient amount of fusion to assure that the wool will not loseits proper position.

The wool is so fragile that flakes from it become scattered throughoutthe tube. Upon attaining suflicient heat to decompose, the alkali oralkaline earth metals in these flakes properly serve as a scavenging orgetter for foreign gases all along the length of the tube. In any case,the presence of the flakes is not detrimental in any way. It will thusbe seen that the provision of this wool serves several distinctfunctions: it forms an electrode support, a cathode screen, a foreigngas scavenger, an amalgamator and an eifective mitigator of sputtering.

Our invention may be modified. without departing from our invention, andwe therefore desire to be extended protection as defined by the scope ofthe appended claims.

What we claim is:-

1. In a gaseous electric discharge device, a

sealed tube having electrodes therein, and a supporting means of glasswool for maintaining each of said electrodes in spaced relation withsaid tube, said supporting means completely encircling the electrode andcovering in contacting relation a substantial portion of the length ofthe active end thereof.

2. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and glass wool for maintaining each of saidelectrodes in spaced relation with said tube, the glass wool completelyencircling each electrode and covering a substantial portion of thelength thereof and extending an appreciable distance beyond the activeend of the electrode.

3.'In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a fibrous silicate compound of alkali oralkaline earth metals disposed between said electrodes and between eachof said electrodes and said tube.

4. In a gaseous electric. discharge device, a sealed tube having.electrodes therein, and a fibrous silicate compound of alkali oralkaline earth metals between said electrodes.

5. In .a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a fibrous silicate compound of alkali oralkaline earth metals supporting and in contact with the active end ofeach of said electrodes in said tube.

6. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a vitreous fiber adjacent and in contact withthe active end of each of said electrodes as a supporting meanstherefor.

7. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, a supporting means comprising a material in a finelydivided condition between the active end of each of said electrodes andsaid tube, said supporting means being adapted to fuse with theelectrode by a slight amount thereby creatinga bond between said meansand said electrode.

8. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a fibrous gas scavenging material immediatelyadlament the active end of each of said electrodes adapted to absorb thereleased gases normally occluded in said electrodes.

9. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a. fibrous gas scavenging material completelyencircling and in contact with the active end portion of each of saidelectrodes adapted to scavenge the released gases normally occluded in 4said electrodes. I

10. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, .and a finely divided fusible material in said tubeadjacent and in contact with the active end of I each of said electrodesfor slight fusion by the heat therefrom, said material upon slightfusion being adapted to release a gas scavenging element adapted toentrap and retain foreign gases present in said tube.

11. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a finely divided slightly fusible materialencircling and contacting the active end of each of said electrodes,said material upon fusing by a limited amount under heating and by itselectrodes being adapted to release a gas absorbing element adapted toentrap and retain gases normally occluded by said electrode.

12. In a gaseous electric discharge device, a sealed tube havingelectrodes therein, and a fibrous compound of silicate and alkali oralkaline earth metals in said tube adjacent and in contact with theactive end of each of said electrodes, said compound being adapted topartially fuse under the heat from said electrode, said compound uponfusion being adapted to release said alkali or alkaline earth metals,said alkali or alkaline earth metals being adapted to act as a scavengerfor foreign gases after such release.

13. In a gaseous electric discharge device containing an amount ofmercury, a sealed tube having electrodes therein, and glass wool meansadjacent and in contact with the active end of one of said electrodesfor entrapping a quantity of the mercury during inoperation of said tubewhereby vaporization thereof occurs immediately upon reheating of saidelectrodes.

14. In a gaseous electric discharge device containing an amount ofmercury, a sealed tube having electrodes therein, and a materialcontaining an alkali or alkaline earth metal immediately adjacent and incontact with the active ends of said electrodes for partial fusion, andrelease of said alkali or alkaline earth metal by the heat thereof, saidalkali or alkaline earth metal upon release being adapted to form anamalgam with a portion of said mercury during inoperation of said tubewhereby an amount of said mercury will promptly evaporate uponsubsequent re-heating of said electrodes.

15. In a gaseous electric discharge device, a sealed tubehavingelectrodes therein, and a support. for each of said electrodescomprising a fibrous slightly fusible material containing an alkali oralkaline earth metal, said support encircling each of said electrodesand covering in contacting relation a substantial portion of the outersurface of the active end thereof, said support upon slight fusion beingadapted to release a quantity of said alkali or alkaline earth metal,said alkali or alkaline earth metal upon release being adapted to serveas a getter for foreign gases in said tube.

16. In a gaseous discharge device including an electron dischargecathode positioned to be bombarded by positive ions travelling theretofor further electron liberation, a screen of glass wool for said cathodeencircling the emission end thereof, said screen extending along aportion of the length of said cathode and comprising a means for forcingthe said positive ions to enter the interior of said cathode forneutralization.

17. In a gaseous electric discharge device including an electrondischarge cathode positioned to be bombarded by positive ions travellingthere to for further electron liberation, a screen of glass wool forsaid cathode encircling the emisslon end thereof and to extend forwardlythereof by an appreciable amount, said screen extending along a portionof the length of said cathode and comprising a means for forcing saidpositive ions toward the center of said cathode for neutralization.

18. In a gaseous discharge device, a sealed tube, an electron dischargecathode positioned in said tube to be bombarded by positive ionstravelling thereto for neutralization, means for supporting said cathodein spaced relation with said tube, said means being composed of asilicate compound wool-like structure containing an alkali or alkalineearth metal encircling said cathode at the open end thereof, said woolcomprising a screen for forcing said positive ions toward the center ofsaid cathode for neutralization, said wool being adapted to partiallyfuse under the heat from said cathode and upon such fusion to release anamount of said alkali or alkaline earth metal, said alkali or alkalineearth metal being adapted to act as a scavenger of any foreign gases insaid tube.

19. The combination as set forth in claim 18 wherein said means extendsforwardly of the open end of said cathode by an appreciable amount.

20. In a gaseous discharge tube having an envelope enclosing a gasfilling, an electrode disposed within said envelope and having acylindrical outer surface concentrically spaced from said envelope, anda wrapping of glass wool covering the exterior surface of the active endportion of said electrode and substantially filling the space betweenthe electrode and envelope, said wrapping of glass wool extendinginwardly of the envelope beyond the active end of the electrode.

HARRY A. STONE.

FRANK SCHAEFER.

